A. Field of the Invention
This invention relates to typewriters, printers and like machines, and particularly to a ribbon drive mechanism for use in such machines.
B. Description of the Prior Art
IBM Technical Disclosure Bulletin, Vol. 19, No. 7, December, 1976 discloses an erase ribbon lift and advancing mechanism which includes a ratchet and pawl driving mechanism, vertically moveable error correction ribbon supply and take-up spools, vertically moveable ribbon guides, and means to achieve a constant ribbon feed increment regardless of the diameter of the ribbon on the take-up spool.
The vertically moveable ribbon guides in the IBM mechanism lift the error correction ribbon into position for error correction. When the error correction ribbon is lifted by two ribbon guides of the type which have openings through which the ribbon passes, it is possible for the ribbon to become caught and not feed or feed improperly in either or both of the moveable ribbon guides. The present invention reduces the possibility of the ribbon being so caught by providing mechanism whereby only one of the ribbon guides is vertically moveable. In addition, to prevent looseness of ribbon between the vertically moveable ribbon guide and the take-up spool when they are in the lowered position, means are provided for the take-up spool to be vertically moveable with the ribbon guide.